This invention relates to manually operated cycle-type transport devices, and more particularly to a handcrank wheelchair.
Racing type wheelchairs, sometimes called hand cycles, have been designed for persons who lack use of their legs. These wheelchairs often have a three wheel design, with two wheels in back and a third wheel in front. The driver sits in a seat between the front and rear wheels.
Conventional racing wheelchairs are operated in a manner similar to xe2x80x9cstreetxe2x80x9d type wheelchairs, by pushing on the top of a circular rail outside the rear wheels. Steering is accomplished by turning a steering handle connected to a front wheel.
Alternative wheelchair designs, for both racing and non racing wheelchairs, have attempted to use handcranks to activate the rear wheels. U.S. Pat. No. 4,274,651, to Dumont, entitled xe2x80x9cWheelchairxe2x80x9d, describes a two-wheeled wheelchair of this type. U.S. Pat. No. 4,758,013, to Agrillo, describes a three-wheeled handcrank wheel chair. Each of these patents describes a hand crank and chain drive assembly associated with each rear wheel. Steering is accomplished by independently rotating the rear wheels.
One aspect of the invention is a sport wheelchair, having a frame tube, a pair of rear wheels, and a single front wheel. A rear axle connects the rear wheels to each other, using struts to support the rear wheels under the frame tube.
A front fork connects the front wheel to the frame tube, such that the front wheel may turn relative to the frame tube for steering. The seat is attached to the frame tube between the front tire and the rear tires. The wheelchair is driven with a handcrank assembly in front of the seat, having a handcrank axle rotatably connected to the frame tube and having a handcrank rigidly attached to each end of the handcrank axle. A steering handle extends generally upwardly from the front fork, and is operable to change the direction of the front wheel. A gearing mechanism has a front sprocket operable to turn in response to rotation of the handcrank axle, at least one rear sprocket operable to turn the rear axle, and a chain connecting the front and rear sprockets. Derailer type gearing, as well as braking, can be implemented in a manner similar to mechanisms used on conventional bicycles.
An advantage of the invention is that it is designed to make the best use of the driver""s upper body strength. The motion is efficient, and at the same time, gears and other active mechanism are placed safely out of the way of the driver.